Components of an internal combustion engine of a vehicle generate noise during operation. For example, an engine structure including a rocker cover, fuel rail, fuel lines, and other base engine and attached components radiate noise that is created by combustion, fuel pressure pulsation (vibration), fuel system pump and injector operation, and mechanical noise generated by an engine. The engine noise generated by these components may be an inconvenience or distraction to occupants of a vehicle or other persons nearby.
In addition, an exhaust gas recirculation (EGR) system may be connected to the engine. The EGR system includes a pipe extending from the engine to recirculate a portion of exhaust gas exiting the engine back into cylinders of the engine under certain conditions. The exhaust gas exits the engine at a high temperature. As result, the exhaust gas flowing in the EGR pipe heats the EGR pipe. The heat is then radiated from the EGR pipe and heats surrounding components. Depending on the construction or material of the surrounding components, the heat from the EGR pipe may affect the surrounding components.
Attempts have been made to address the issues above. In one arrangement, a combination of foam and plastic shell is positioned adjacent to the engine in an effort to attenuate sound and protect components from heat radiated from the EGR pipe. In another arrangement, a fiber mat has been positioned adjacent to engine. However, these arrangements do not provide sufficient noise attenuation or sufficiently shield engine components from heat.
Accordingly, it is desirable to provide an acoustic and thermal cover assembly configured to attenuate engine noise to improve passenger comfort and shield engine components against heat to improve service life of those components.